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Probably not the sexiest of topics when it comes to learning about wine, however trellising and training vines have a surprising impact on the end product. A trellis system is the wood and wire construct which hold up the vines and allow the viticulturist and/or winemaker to effectively position the vine to grow in the optimal position. The type of trellis and training system they choose depends on many factors, such as the vigour of the vine, whether the grape variety naturally grows downwards or upwards and whether the vine is to be spur or cane pruned or both. This decision, while not permanent – a winemaker can choose to change a trellising system at some cost, is extremely important as a trellising system can influence the amount of shade or sun on grapes, how easy mechanisation will be, the amount of heat reflected onto the fruit from the ground, the ability to mitigate frost damage and the effect of wind. So, it’s easy to understand why trellising and training systems are complex with many different iterations. However, they can generally be categorised as either non-divided canopy systems or divided canopy systems. Although let’s also not forgot that many vines across the globe aren’t trained at all.
Below we’ll discuss some of the more common examples of trellis and training systems, but this list is by no means the be all and end all. It is also worth noting that there will be the odd mention of pruning techniques, which are related to but are not part of a trellising specifically. Pruning refers to the cutting and shaping of the cordon or “arms” of the grapevine in winter. There are 2 main types of pruning;
- Spur Pruning: If left on the vine, a green shoot will harden to become a woody cane after vintage and along the cane there are several buds, which will each produce a shoot during spring budbreak. A spur is created when a woody cane is cut back to two buds, which next season will become green shoots, then harden to woody canes, and the decision is made again as to which cane to fully remove, and which to prune back to 2 buds.
- Cane Pruning: Requires the grower to retain one spur and one cane. The number of buds left on the cane can vary from six to over a dozen. The buds on the two-year-old cane each produce green shoots that will produce a season’s fruit. After harvest the entire two-year-old main cane and its fruiting canes are removed. Then, one of the one-year-old canes from the spur is selected and this becomes the next season’s cane.
Non-Divided Canopy Systems
Non-divided canopy systems have a single fruit zone which means they are less expensive to establish and maintain, which is one of the reasons why they are so popular across the globe.
- Single and Double Guyot
These are the most common trellising systems and are often partnered with Vertical Shoot Positioning. Winemakers in cooler regions use this training method as it can invigorate shoot growth while ensuring that buds and fruit are adequately exposed to sun, which is particularly important in cooler regions to achieve optimum ripeness. It is best used with low to moderate vigour sites & varieties. When used with high vigour vines such as a Sauvignon Blanc vineyard in Marlborough NZ the canopy can become dense and therefore leaf removal will be required to improve bunch exposure and reduce disease risk. Although the single guyot is often used in low vigour sites and is common throughout Burgundy.
- Umbrella Kniffin
This Trellising system is a simple trellis construction which uses head trained vines and long canes (up to 20 buds on each) that originate from renewal spurs at or near the top of the trunk. It keeps the fruit high and well exposed but can be costly as requires annual tying of canes which has to be done manually.
- High Bilateral Cordon
This is essentially a high trained trellis where cordons remain as semi-permanent extensions of trunk & replaced every 5 years. It is an efficient system as it is adaptable to mechanical pruning and mechanical shoot positioning.
Divided Canopy Systems
Divided Canopy Systems have two fruit zones and expose more of the vine’s foliage to sunlight, in theory this increases fruit production while maintaining quality. These systems are particularly suited to high vigour varieties and are really quite inappropriate in low nutrient soils and areas where rainfall or irrigation is limited. These systems can be further categorised into those with horizontally divided canopies or vertically. Horizontally divided canopy systems are more common although they do require wider row spacing due to training the canopy on either side of the trunk. A major downside of these systems is that they are expensive to establish due to the complex positioning of the wires required to train the vine into these split canopy positions.
- Geneva Double Curtain – Horizontal
This system divides the canopy into two parallel hanging curtains with the fruiting zone positioned at the top of the canopy. These systems are normally cordon-trained and spur pruned which allows the winemaker to retain a greater bud count on high capacity vines. This is often used in high vigour sites to maximise yields, such as Marlborough.
- Lyre – Horizontal
This system was developed by Alain Corbonneau in Bordeaux in the 1980s, and more recently has become popular in California. It is particularly well adapted for upright growing varieties for medium to high yield vineyards, although it is difficult to mechanise which can increase costs of maintaining the vineyard if they choose to hand harvest and prune. Most commonly used in New World regions, with many Californian producers initially choosing this system before adapting to Guyot systems.
- Scott-Henry – Vertical
Scott Henry owned the Henry Estate Vineyard in Umpqua Valley, Oregon and was alarmed at the declining quality of his fruit. He took it upon himself to design a unique four-pronged trellising system that exposed the grape bunches to maximum sunlight – the “Scott Henry Trellis System” was established. This system can improve grape yields and quality in high vigour cool climate vineyards with the shoots trained both upward and downward using cane pruning. A region which specialises in this system is Oregon, and vineyards which have a large concentration of Missoula Flood soils. These soils contain relatively balanced amounts of sand, silt and clay and are found along the Columbia Gorge banks and Willamette Valley floor. The topsoil is so fertile that the Scott-Henry system is required when growing pinot noir to maintain the vines vigour. It isn’t just Oregon where this trellising system is used, in fact Oyster Bay has 5,240 acres of Scott-Henry planted in both New Zealand and Australia, some of the largest Scott-Henry systems in the world.
- Smart-Dyson – Vertical
This system is similar to the Scott-Henry but is spur pruned with the spurs pointing upwards and downwards from a mid-height cordon. It can be mechanically pre-pruned and machine harvested. It was designed by Richard Smart and John Dyson to improve yield and wine quality by providing a better grape to foliage balance.
A trellis system provides support for the shoots and fruit, since the vine is not able to support itself and can help to spread the shoots out more evenly. Evenly spread shoots improve airflow and light penetration in the canopy which in turn reduces disease pressure. However, this doesn’t mean that vines without a trellising system are automatically less healthy than their trellised counterparts.
The Goblet system is essentially a vine which has grown its own shape naturally, they are also known as Bush vines or head trained. This non-trellised system is great for sun protection but terrible for disease management as there is less air circulation and spray penetration. However, they require little irrigation to maintain moderate water stress through ripening which makes them a good choice for more arid regions where irrigation isn’t possible. They can also provide high yields/hectare using high density planting. It is also worth remembering that in some regions non-trained systems are the only option for example in steep slope situations. Varieties such as Syrah, Grenache, Carignan, Pinotage or Chenin are particularly well suited to non-trellised systems. Therefore it is commonly found across South Africa and also in the Rhône valley. Finally, non-trellised vines require very little canopy management which can make them relatively inexpensive to establish and maintain although this does mean they are ill equipped for mechanisation which can add to the cost of maintaining as labour because increasingly more expensive